This invention relates to fluorescent x-ray spectroscopes which can be used both as a wavelength-dispersion type and as an energy-dispersion type.
Fluorescent x-ray spectroscopes are for analyzing the constituent elements of a sample by irradiating the sample with excitation x-ray to thereby generate fluorescent x-ray and can be divided into the wave-dispersion type and the energy-dispersion type, depending on the method of detecting the fluorescent x-ray.
As shown in FIG. 3, a wavelength-dispersion type spectroscope comprises an irradiation chamber 21 and a detection chamber 22 provided next to each other, the irradiation chamber 21 being provided with an x-ray source 23 for irradiating a sample S set at a fixed position with a beam of excitation x-ray emitted therefrom. The fluorescent x-ray, which is generated by this irradiation of the sample S, is directed into the detection chamber 22. The detection chamber 22 contains therein at least a light-dispersing means, such as a dispersing element 24, and a detector 25 corresponding thereto such that the fluorescent x-ray introduced into the detection chamber 22 is dispersed by the dispersing element 24 into different wavelength components to be detected by the detector 25. The dispersing element 24 and the detector 25 are so controlled that the detector 25 will rotate by an angle of 2.theta. as the dispersing element 24 is rotated by .theta. such that fluorescent x-ray can be scanned over all its range of wavelength.
In the case of a spectroscope of the energy-dispersion type, as shown in FIG. 4, an x-ray source 23 and a detector 26 corresponding to its energy-dispersion are attached to its irradiation chamber 21. The fluorescent x-ray, which is generated inside this irradiation chamber 21 from the sample S by the irradiation of the excitation x-ray from the source 23, is not dispersed, and all its components are taken in by the detector 26 which is adapted to detect it at each of its energy levels.
Spectroscopes of each of these two types have their own advantages and disadvantages. The wavelength-dispersion type provides a better resolution and is capable of distinguishing individual elements even if they are at mutually near-by wavelength regions, but the angles of the dispersing element 24 and the detector 25 must be varied correspondingly for effecting a scan when elements scattered over a wide wavelength region are to be analyzed. This takes a relatively long period of time, and it is a disadvantage if a quick analysis is desired. The energy-dispersion type, on the other hand, can complete an analysis very quickly, say, within a few seconds or within a few minutes, even if the fluorescent x-ray is spread over a wide wavelength range because the spectrum of such a ray can be analyzed at the same time. It is therefore suitable for a quick analysis, but since there is a limit to the counting rate of the intensity of the fluorescent x-ray, it is difficult to carry out the analysis of a very small amount of an element.
For this reason, a sacrifice had to be made either in terms of the time of analysis or the accuracy of analysis when a prior art device was used. In other words, there were frequently situations where the primary object of analysis could not be accomplished. If devices of both types are to be made available, on the other hand, not only is it costly to be so prepared but also it is cumbersome to set and reset a sample from one device to another.